Classifications

• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B17/00—Guiding record carriers not specifically of filamentary or web form, or of supports therefor
  • G11B17/02—Details
  • G11B17/022—Positioning or locking of single discs
  • G11B17/028—Positioning or locking of single discs of discs rotating during transducing operation
  • G11B17/0284—Positioning or locking of single discs of discs rotating during transducing operation by clampers

Definitions

• disc-shaped elements such as floppy disks, "floppy-discs”, etc. are increasingly used as a recording medium.
• word processing typewriters computer peripherals, recording and broadcasting devices
• these recording media must be mounted and centered on the rotor of a drive motor.
• the recording medium generally has a circular opening in its center. It is slid laterally above the motor rotor, after which an automatic centering device is put in place which generally comprises a cylindrical pin engaging in the opening of the recording medium and in a centering housing which has the motor rotor shaft.
• the centering devices known at the present time are designed in such a way that the shaft is a complicated part having numerous surfaces, the machining of which must be carried out with high precision.
• this shaft has anyway two cylindrical surfaces, one of which ensures the centering of the rotor in its support bearing and the other ensures the centering of the recording medium with respect to the rotor.
• the machining of these two surfaces cannot be carried out easily during two successive machining operations.
• the constitution of these shafts is such that the two cylindrical surfaces which must be strictly coaxial, have an extremely large difference in diameter between them. The object of the invention is thus to simplify the construction of these trees and therefore reduce their cost price.
• the subject of the present invention is an automatic centering device for a recording medium on the rotor of an engine, comprising a shaft integral with the rotor, supported by a bearing and having two coaxial cylindrical surfaces, a first of which ensures the centering of the rotor in the bearing and a second ensures the centering of the recording medium on the rotor, this second surface being an interior surface.
• the object indicated above is achieved by the fact that the first cylindrical surface is an interior or exterior surface having a diameter substantially equal to or greater than that of the second surface.
• FIG. 1 is a sectional view through the axis of a known centering device
• FIG. 2 is a view in partial axial section of a motor comprising a first embodiment of the centering device according to the invention
• FIG. 3 is a view similar to FIG. 2 showing a second embodiment of the centering device.
• the stator 2 of the motor may include an arrangement of stator coils with or without an iron core shown diagrammatically at 3, these coils being held in place between two support parts 4 and 5, so as to constitute the bearing part of the engine.
• the support 4, 5 supports a bearing body 6 which has a cylindrical bore 7 in which are driven two small diameter ball bearings 8.
• the internal raceways 9 of the bearings 8 are driven on a central bearing 10 of a shaft
• the shaft 11 has a second bell-shaped flange 15 limited forwards by a flat front surface 16 on which the disk 1 rests and in the housing of which the movable part 17 of the device is introduced. centering.
• This mobile part is known per se and it will not be necessary to describe it in detail here. We know that it comprises in particular a centering cone formed by a multitude of tongues 18 connected to each other and maneuvered so as to engage simultaneously against an internal cylindrical surface 19 of the flange 15. At the same time as the piece of centering 18 is introduced into the housing 15 another part of the mobile device 17 comprising an annular flange 20 comes to press axially the central part of the floppy disk 1 against the surface 16.
• FIGs. 2 and 3 show motors for driving a recording medium which are arranged so as to be able to cooperate with a movable centering device such as device 17 or a similar device, but operating in principle in the same way.
• stator 21 of the motor which comprises one or more coils 22 mounted on a fixed support consisting of two parts 23 and 24.
• a bearing support 25 which plays the same role as the part 6 of FIG. 1 and which in particular has an internal cylindrical surface 26 in which the external raceway 27 of a bearing 28 is driven.
• the rotor 29 of FIG. 2 comprises a shaft 30 which is a tubular metal part having a cylindrical inner face 31 and an also cylindrical outer face 32 coaxial with the face 31. These two surfaces are limited at one end by an erect planar face 23 which corresponds to the face 16 of the motor of fig. 1 and at the other end by another flat face, perpendicular to the axis of the motor, designated by 34 and on which is fixed the circular part 35 which supports the magnets 36.
• the inner raceway 37 of the bearing 28 is driven onto the outer surface 32, the rotor further comprising a spacer ring 38 between the sheet 35 and the bearing 28.
• the first cylindrical surface which requires a high precision adjustment is an external surface with a diameter greater than that of the second surface, which is an internal surface extending over the entire length of the tubular part 30.
• the bearing 28 is therefore a bearing with bearing with a diameter significantly greater than that of the bearing 8 in the embodiment of FIG. 1. It was found that this difference in the diameters of the bearings had no effect on the accuracy of the centering and that on the other hand it was much easier during the machining of the part 30, to realize with the desired tolerances the two surfaces 31 and 32. As the diameters of these two surfaces are very similar, the part 30 can be clamped in a machine tool by its end turned on the side of the rotor 29, while the two surfaces 31 and 32 as well as the surface 33 are machined from the opposite side.
• a tree such as the tree 30 can be made in dimensions corresponding to those of the bell-shaped tree 11 in FIG. 1 and in the same metal, for example aluminum alloy in much simpler and consequently much less costly machining conditions than what was known until now without the precision when centering the support d the record is not put in default.
• the surface 32 could also be machined so that it directly constitutes the inner raceway of the bearing 28.
• the inner ring 37 could be entirely eliminated, the balls of the bearing held in place by their cage , being engaged from the face 33 on the surface 32 until the bearing is correctly positioned with respect to the stator.
• Fig. 3 shows a drive motor which corresponds to another embodiment of the device according to the invention. Whereas, in the devices of figs. 1 and 2 the magnets of the rotor were located opposite the centering means of the recording medium relative to the stator, they are in the embodiment of FIG. 3 on the same side.
• coils 39 which are mounted on a stator frame 40 cooperating with a cap 41 to fix a bearing body 42 which is tubular in shape and has a cylindrical extension 43 supporting by its outer face a bearing 44
• the bearing itself is reduced to two rows of balls held in place by a cage and mounted between an inner rolling surface which constitutes the external face 45 of the extension 43 and an external rolling surface which constitutes the internal face 46 of a tubular shaft 47.
• the latter is provided at one end with a flange 48 on which is fixed the sheet 49 carrying the magnets 50.
• the first and the second of said coaxial cylindrical surfaces are located in the extension of one of the other. They can have the same diameter or substantially equal diameters.
• the second surface is the surface 46 which extends forward from the bearing, while the first surface is that which ensures the rolling of the balls 44.
• the first surface is that which ensures the rolling of the balls 44.
• an insert can also be arranged inside the tree 47 by any suitable means.

Landscapes

• Manufacture Of Motors, Generators (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=4260083

Family Applications (1)

Country Status (3)

Families Citing this family (1)

Family Cites Families (5)

• 1984
  • 1984-07-26 CH CH362984A patent/CH657932A5/fr not_active IP Right Cessation
• 1985
  • 1985-07-17 WO PCT/CH1985/000115 patent/WO1985003837A2/fr not_active Ceased
  • 1985-07-17 EP EP19850903203 patent/EP0191027A1/de not_active Withdrawn

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events